5.1 Residential Combustion - Natural Gas

    Category ID Description EIC
    283 Domestic - Natural Gas - Space Heating 61060601100000
    284 Domestic - Natural Gas - Water Heating 61060801100000
    285 Domestic - Natural Gas - Cooking 61061001100000
    2540 Domestic - Natural Gas - Other 61099501100000

    Introduction

    The Residential Combustion sector consists of greenhouse (GHG) emissions from sources from residential household appliances that are not required to be permitted or registered by the Bay Area Air Quality Management District (Air District). ‘Permitted’ is defined as requiring a permit or registration issued by the Air District to operate a facility and/or equipment in the San Francisco Bay Area (SFBA). Even if not permitted, residential combustion equipment may be subject to local ordinances and building codes governing their installation and operations (i.e., water heaters). The Air District rules mandate the allowable emissions from these appliances at the point of sale but do not track individual equipment performance or emissions. The following categories account for emissions from the combustion of natural gas in the Residential Combustion sector:

    • Category 283 – Residential Space Heating (Natural Gas-Fired Furnaces)
    • Category 284 – Residential Water Heating (Natural Gas-Fired Water Heaters and Boilers)
    • Category 285 – Residential Cooking (Natural Gas-Fired Stoves/Ovens)
    • Category 2540 – Residential Other Appliances (Natural Gas-Fired Other Appliances)

    The ‘Other Appliances’ source category accounts for combined natural gas combustion emissions from appliances such as pool water heaters, spa and hot tub heaters, clothes dryers, and barbeque grills.

    Natural gas, that is used as fuel to power residential equipment, is composed primarily of methane with small amounts of other hydrocarbons such as ethane, propane, and butane (see Uncertainty section). The GHG emissions reflected herein include combustion by-products carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), emitted from the combustion of natural gas across a variety of residential appliances. Emissions from combustion of natural gas equipment in the Commercial sector are accounted for in Categories 307_com and 1591.

    Methodology

    These categories are considered area sources as they account for emissions from combustion devices that are not permitted by the Air District and hence are not systematically or annually reported. The data used to estimate emissions for these sources must be extracted from either the California Air Resources Board (CARB) or California Energy Commission (CEC) databases. The methodology used to calculate emissions for the reported base years for these source categories is as follows:

    Base Year(s) Emissions county,pollutant =

    Activity Data × Emission Factorpollutant × Control Factorpollutant × Fractioncounty × Fractionin District × GWP pollutant

    Where:

    • Base Year: is a year for which activity / throughput data is reported by CEC and/or CARB, and available.
    • Activity Data: is the throughput or activity data for applicable reported base years. This data may be determined in one or two ways:
      • Apportioning Larger-Scale Data: Throughput data from a larger domain, such as state or national level, is scaled using the proportion of a representative metric in the regional domain relative to the larger domain. For example, the ratio of a county’s population to the state population can be used as a scaling factor to determine the county throughput from state-level throughput.
      • Using Local Sources: Alternatively, data from a locally published and verifiable source may be used, such as the county-level natural gas usage data provided by the CEC.
    • Emission Factorpollutant: is a factor that allocates an amount of emissions, in mass, of a particular pollutant by unit of activity data. For example, tons of CO2 per gallon of gasoline burned or pounds of N2O per million standard cubic feet (MMSCF) of natural gas combusted. This factor generally comes from a published literature source such as USEPA AP-42 (USEPA, 1998) or CARB’s Mandatory Reporting Requirement (MRR) for Greenhouse Gases (CARB, 2019).
    • Control Factorpollutant : is a fractional ratio (between 0 and 1) that captures the estimated reduction in emissions as a result of Air District rules and regulations.
    • Fractioncounty : is the fraction of total regional emissions (between 0 and 1) estimated to be allocated to a particular county. It is typically derived from regional socioeconomic metrics and/or actual county-level throughput data.
    • Fractionin District : The Air District jurisdiction covers only a portion of Solano and Sonoma County. For this reason, additional allocation must be made for these counties to determine the proportion of the county’s emissions occurring within the Air District’s jurisdiction.
    • GWPpollutant is the Global Warming Potential of a particular greenhouse gas (GHG) pollutant. The current version of the GHG emissions inventory incorporates the global warming potential (GWP) reported in the Fifth Assessment report of the Intergovernmental Panel for Climate Change (IPCC, 2014). The GWPs for the three principal GHGs are 1 for carbon dioxide (CO2), 34 for methane (CH4), and 298 for nitrous oxide (N2O), when calculated on a 100-year basis with climate-carbon feedback included.

    Once base year emissions are determined, historical backcasting and forecasting of emissions relative to the base year emissions are estimated using growth profiles as follows:

    Current Year Emissionscounty = Base Year(s) Emissioncounty x Growth Factor

    Where:

    • Growth Factor: is a scaling factor that is used to derive historical emissions estimates for years for which activity data and/or emissions are not available, and to forecast emissions for future years, using surrogates that are assumed to be representative of activity and/or emissions trends.

    More details on the inputs and variables used above are provided in the following subsections:

    Activity Data

    Activity data for these categories is reported by the CEC (CEC, 2023a) as natural gas (NG) consumption usage for each Bay Area County. The usage represents total natural gas consumed in the Residential sector in energy units of million therms (MMTherms). The usage per county, once converted to units of MMSCF, is then proportioned into each of the residential source categories by multiplying the county usage by the estimated fraction of natural gas consumed in each category. The fraction is based on CEC’s 2019 Residential Appliance Saturation Study (RASS; CEC, 2020a) (see table below). This approach is applied to reported base years data from 2011 to 2022, for which natural gas consumption usage data are available from the CEC.

    Space Heating

    Category 283

    Water Heating

    Category 284

    Cooking

    Category 285

    Other

    Category 2540

    39.31%

    54.90%

    3.30%

    2.49%

    Not all of the natural gas that is delivered is combusted; some is lost due to post-meter leakage. Therefore, an additional natural gas loss based on the leakage rate of 0.50% for residential appliances (CEC, 2018) is applied.

    County Distribution / Fractions

    County distribution is determined by using base year data for 2022 for Residential sector natural gas usage from the CEC.

    ID Description ALA CC MAR NAP SF SM SNC SOL SON
    2540 Domestic - Natural Gas - Other 0.21 0.17 0.05 0.02 0.12 0.11 0.23 0.04 0.06
    283 Domestic - Natural Gas - Space Heating 0.21 0.17 0.05 0.02 0.12 0.11 0.23 0.04 0.06
    284 Domestic - Natural Gas - Water Heating 0.21 0.17 0.05 0.02 0.12 0.11 0.23 0.04 0.06
    285 Domestic - Natural Gas - Cooking 0.21 0.17 0.05 0.02 0.12 0.11 0.23 0.04 0.06

    BAAQMD Jurisdiction Fraction

    A second apportionment is applied to account for emissions that occur in the portion of Solano and Sonoma counties that are within the Air District’s jurisdiction. The remaining area in these counties is covered by other Air Districts.

    For these categories, ABAG’s population data based on their Plan Bay Area 2050 was used to develop the percentage of Solano and Sonoma County populations within the Air District boundary. (ABAG, 2021). ABAG summarizes population into Travel Analysis Zone (TAZ) such that county totals are estimated by summing the population by TAZ within the Bay Area’s jurisdiction and divided by the total county-wide population to estimate the percentage of population within the SFBA for Solano and Sonoma counties. These proportions are shown below:

    County

    % of Population within the District’s jurisdiction

    Solano

    0.70

    Sonoma

    0.86

    Emission Factors and Local Controls

    The emission factors for this category are dependent on the control factors. The combination of these two factors produces the Effective Emission Factor used in the emissions calculations. The Effective Emission Factor represents average emissions emitted from a natural gas combustion boiler/heater with add-on pollutant controls included. These controls may come in the form of a physical control device or as an emissions limit stipulated by Air District regulation or permit conditions. For example, the Effective Emission Factor for category 283 in 1990 for N2O was 2.2 lb/MMSCF, however, this same factor in 2022 is around 0.64 lb/MMSCF due to requirements in Regulations 9-4 and 9-6 that progressively lower the allowable nitrogen oxides emitted from natural gas residential space heaters and water heaters sold in the Bay Area.

    To compile the effective emission factor for each year, either the emission factor or control factor is adjusted to account for fleet turnover and/or compliance with the Air District regulation. In this case, the emission factor determined to be applicable in the year 1990 is held constant from 1990 onwards, and the evolving control factor is used to adjust the Effective Emission Factor.

    The 1990 emission factors used for these calculations are presented in the table below. The impact of controls on these emissions factors is discussed in the following section.

    Pollutant

    Emission Factor (lb/MMSCF)

    Reference

    CH4

    2.26

    EPA 40 CFR Part 98 Subpart C, 2016

    N2O

    2.2

    EPA AP-42, Chapter 1.4, 1998 (N2O Uncontrolled)

    CO2

    120,019

    EPA 40 CFR Part 98 Subpart C, 2016

    In 1983 and 1992, the Air District passed two rules that progressively reduce the allowed nitrogen oxides emissions coming from natural gas-fired furnaces and water heaters: Regulation 9, Rule 4 (BAAQMD, 2023b) applies to all residential natural gas-fired furnaces under category 283 while Regulation 9, Rule 6 (BAAQMD, 2023a) targets emissions from all residential natural gas-fired water heaters and boilers (category 284). The rules apply at the point of sale such that, following the effective date of the Rules, only those natural gas-fired furnaces, water heaters, or boilers, that meet the requirements of the regulations can be offered for sale within the Air District. There are currently no Air District regulations that apply to natural gas combustion from residential cooking and other residential combustion processes (categories 285 and 2540).

    The timeline of emissions standards put into place by each rule is outlined below:

    Regulation 9, Rule 4

    Year

    Regulatory Standard

    Target Pollutant

    Target Pollutant Limit (lb/MMSCF)

    Affected

    Co-pollutant(s)

    Affected Co-pollutant limits

    (lb/MMSCF)

    1983

    Limit NOx for newly installed furnaces

    NOx

    172

    N2O

    2.2

    1984

    Limit NOx for newly installed boilers

    NOx

    93

    N2O

    0.64

    2024

    Limit NOx for newly installed furnaces

    NOx

    33

    N2O

    0.23

    2029

    Require installation of Zero NOx furnaces

    NOx

    0.00

    All (CO2, CH4, N2O, PM, SO2, TOG)

    0.00

    Regulation 9, Rule 6, Section 301

    Year

    Regulatory Standard

    Target Pollutant

    Target Pollutant Limit (lb/MMSCF)

    Affected

    Co-pollutant(s)

    Affected Co-pollutant limits

    (lb/MMSCF)

    1992

    Limit NOx for newly installed boilers

    NOx

    172

    N2O

    2.2

    1993

    Limit NOx for newly installed boilers

    NOx

    93

    N2O

    0.64

    2009

    Limit NOx for newly installed boilers

    NOx

    23

    N2O

    0.23

    2027

    Require installation of Zero NOx boilers

    NOx

    0.00

    All (CO2, CH4, N2O)

    0.00

    Both rules have been amended to require installation of zero NOx emitting furnaces, water heaters, and boilers in the near future. The amendments requiring low-NOx boilers only impacts emissions of N2O, whereas the requirement of zero NOx boilers affect all GHG pollutants: CO2, CH4, and N2O. Given the average lifespan of water heaters is 10-13 years (BAAQMD, 1992; BAAQMD, 2007; BAAQMD, 2023c) and ~18 years for furnaces (BAAQMD, 2023c), the control curves are estimated by accounting for the lifespan of each appliance as a fleet turnover rate is combined with the estimated emission factors for low-NOx boilers in the late 1990s (USEPA, 1998) and early 2000s (USEPA, 2016) to comply with the Air District regulations and to determine the ‘controlled’ emissions.

    Historical Backcast

    For historical backcast of natural gas throughput, the CEC natural gas usage by county for the Residential sector from 1990 to 2011 is used to produce a backcast profile. This profile is normalized to the year 2011 and applied to the year 2011 throughput obtained from the latest CEC publication (CEC, 2023a) to determine throughput for years 1990-2011. As explained above, an effective emission factor was then applied from 1990-2011 to estimate emissions for N2O, CO2, and CH4.

    Future Projections

    The CEC publishes an Integrated Energy Policy Report (IERP) every 2 years in which they forecast natural gas usage by an energy provider that accounts for achievable fuel substitution (AAFS) and achievable energy efficiency (AAEE). For all forecasting, a scenario based on a combination of AAFS and AAEE factors that best represents business-as-usual scenario is chosen. Business-as-usual is defined as existing conditions that include impacts from state and federal regulation adopted as of year 2022. To portray business-as-usual forecasting of emissions, the CEC recommends the use of Scenario 3 Programmatic AAFS and AAEE for the Pacific Gas & Electricity (PG&E) regional service area (CEC, 2023c). This forecast does not include the impacts of the following zero-emission appliance standards (ZEAS):

    • CARB’s Zero-Emission Appliance Standard: as of this publication of the inventory, this standard has not been finalized
    • Air District Regulation 9, Rule 6 (BAAQMD, 2023a), whose future impact is already included in the applicable control curve.

    Reductions under Air District Regulation 9, Rule 6 are accounted for only once as a part of the control factor thereby eliminating any double counting errors in the forecast by relying on CEC data which does not include Air District rules in its projections. The use of this projection curve also avoids the inclusion of non-enforceable goals set by CARB.

    Sample Calculations

    An example calculation is provided below to estimate N2O emissions in San Francisco County for year 2022 for area category 283:

    Step 1

    Convert 2022 natural gas usage for Residential sector, obtained from the CEC for San Francisco County, from MMTherms (million therms) to MMSCF (million standard cubic feet)

    128.02 MMTherms

    × 100,000 MMBtu/MMTherms

    ÷ 0.001026 MMBtu/scf

    × 1E-06 MMSCF/scf

    = 12,477 MMSCF

    Step 2

    Apply the fraction of natural gas lost due to leakage

    12,477 MMSCF

    × (1-0.0050)

    = 12,415 MMSCF

    Step 3

    Apply the fraction of natural gas

    usage proportioned for space heating

    12,415 MMSCF

    × 0.3931

    = 4,880 MMSCF

    Step 4

    Apply the 2022 effective emission factor for N2O to the space heating emissions (see Emission Factors and Controls section for more detail)

    4,880 MMSCF

    × 0.64 lb/MMSCF

    = 3,123 lbs

    Step 5

    Convert emissions to million metric tons of CO2 equivalents (MMTCO2eq/year) by applying the GWP of 298 for N2O

    3,123 lbs

    × 1 ton/2000 lbs

    × 0.907185 tonne/ton

    × 298

    ÷ 1E06 tonne/MMT

    = 0.000422 MMTCO2eq

    Assessment of Methodology

    The general methodology for determining emissions for these categories has not changed. However, the determination of natural gas throughput allocated to each category has been significantly upon by the inclusion of post-meter leakage and an updated split between end-use operations by residential category that greatly improves the accuracy of resulting emissions.

    Base Year

    Revision

    Reference

    2022

    1. Used natural gas usage reported by CEC for base years of 2011-2022, backcast, and forecast based on business-as-usual model forecast.
    2. Updated Sonoma/Solano County proportions in the SFBA using ABAG’s Plan Bay Area 2050 projections for 2022.
    3. Updated emission factors based on USEPA AP-42 and Title 40 values
    4. Updated control factors to reflect amendments from Regulations 9-4 and 9-6
    5. Updated end-use fractions of natural gas usage to proportion into each residential category
    6. Used the latest GWP from the Fifth Assessment report of the IPCC.
    1. CEC, 2023a
    2. ABAG, 2021
    3. USEPA, 1998; USEPA, 2016
    4. BAAQMD, 2023
    5. CEC, 2018
    6. IPCC, 2014

    2015

    1. Used single base year of 2010, 1990-2010 data is same as Air District’s BY 2011 estimates
    2. The forecast includes projected reductions based on nonmandated policies and goals.

    3. No controls accounted for in the emissions from adopted Air District regulations

    1. BAAQMD, 2015
    2. Greenblatt, 2013
    3. Greenblatt, 2013

    Emissions

    The table below summarizes greenhouse gas emissions for the base year 2022 in metric tons of CO2 equivalents (MTCO2eq).

    ID Description CH4 CO2 N2O Total
    284 Domestic - Natural Gas - Water Heating 1901.4 2969815.3 1696.0 2973412.7
    283 Domestic - Natural Gas - Space Heating 1361.6 2126708.0 3379.5 2131449.1
    285 Domestic - Natural Gas - Cooking 114.4 178567.6 101.9 178783.9
    2540 Domestic - Natural Gas - Other 86.3 134634.3 76.9 134797.5

    Summary of Base Year 2022 Emissions

    In the Commercial and Residential sector, fuel combustion is the source of the majority of the GHG emissions, primarily from the widespread use of natural gas as the fuel for both commercial and residential equipment. A detail breakdown by category and county is provided below.

    Contribution of Residential Combustion - Natural Gas Emissions by Sector
    Subsector Sector Subsector GHG Emissions (MMTCO2eq) Sector GHG Emissions (MMTCO2eq) % of Sector
    Residential Combustion - Natural Gas Commercial + Residential 5.42 12.85 42.17%

    Contribution of Residential Combustion - Natural Gas Emissions to Regional Total
    Subsector Subsector GHG Emissions (MMTCO2eq) Regional Total GHG Emissions (MMTCO2eq) % of Regional Total
    Residential Combustion - Natural Gas 5.42 65.68 8.25%

    Trends

    The time series chart below shows the emission trends for categories 283, 284, 285, and 2540.

    Summary of Trends

    The historical residential NG combustion emission trends, as expected, follow the CEC NG consumption data for the SFBA. For future trends, the growth of each category, and emissions by pollutant, is restricted by the Air District regulations that limit the pollutant emissions from these categories. For N2O, categories 283 and 284 steadily decline starting from 1990, leveling out only slightly from 2000 to 2022, and are projected to continue a gradual decline in future years. For category 283, emissions for all GHG pollutants are reduced to zero by the year 2046 in complete compliance with Regulation 9, Rule 4 which requires all new furnaces be replaced with zero-NOx alternatives. For category 284, GHG emissions are expected to reduce to zero by the year 2039 due to Regulation 9, Rule 6 requirements set in Section 301. For categories 285 and 2540, only a slight decrease in emissions is predicted based on voluntary fuel switching and replacement with more efficient appliances as these household appliances are not currently regulated. The contrast in trends between categories 283 and 284 versus those of categories 285 and 2540 shows how regulatory requirements can achieve significant reductions in GHG emissions to meet future targets.

    Uncertainties

    Uncertainties in the emissions estimates for these categories primarily stem from the assumptions used to calculate them. These key assumptions include:

    • Based on regional natural gas composition data (CEC, 2020c), the minor proportion of ethane (<5%) found in natural gas is assumed to have similar hydrocarbon and volatility characteristics as the methane present in natural gas (~93.5% or higher), and treated as methane for emissions estimation purposes. This may lead to a methane emissions estimate which is conservative but well within the uncertainty of the estimation method and the natural variation in natural gas composition found in collected samples.
    • Future natural gas consumption trends in the Bay Area are assumed to follow the same trajectory as those for the entire PG&E service area.
    • Future natural gas consumption is assumed to be uniformly distributed across all Bay Area counties.
    • The end-use distribution of natural gas consumption is assumed to have remained relatively unchanged since 2019 and is assumed to mirror the distribution of the broader PG&E service area.

    To reduce these uncertainties in future estimates, the following improvements to the underlying data are recommended:

    • Develop county-level projections based on CEC’s estimates for total PG&E service area consumption and county-level population growth trends.
    • Update residential end-use breakdown using region-specific measurements and/or surveys.

    Contact

    Author: Ariana Husain

    Reviewer: Abhinav Guha

    Last Update: 07/16/2025

    References

    ABAG. 2017. Plan Bay Area 2040. https://planbayarea.org/plan-bay-area-2040

    ABAG. 2021. Plan Bay Area 2050. https://planbayarea.org/finalplan2050

    BAAQMD. 1992. Rule Development Staff Report: Regulation 9 – Inorganic Gaseous Compounds, Rule 6 Nitrogen Oxides Emissions from Natural Gas-Fired Water Heaters . 29 pp. Mohamad Moazed.

    BAAQMD. 2007. BAAQMD Regulation 9, Rule 6: Nitrogen Oxides from Natural Gas-Fired Water Heaters and Small Boilers – Staff Report. 17 pp. Guy A. Gimlen.

    BAAQMD. 2015. Bay Area Emissions Inventory Summary Report: Greenhouse Gases. Base Year 2011. http://www.baaqmd.gov/~/media/Files/Planning%20and%20Research/Emission%20In ventory/BY2011_GHGSummary.ashx?la=en

    BAAQMD. 2023a. Regulation 9- Inorganic Gaseous Pollutants, Rule 6 – Nitrogen Oxides Emissions from Natural Gas-Fired Boilers and Water Heaters. Available at: https://www.baaqmd.gov/~/media/dotgov/files/rules/reg-9-rule-4-nitrogen-oxides-from-fan-type-residential-central-furnaces/2021-amendments/documents/20230315_rg0906-pdf.pdf?rev=436fcdb037324b0b8f0c981d869e684d&sc_lang=en

    BAAQMD. 2023b. Regulation 9- Inorganic Gaseous Pollutants, Rule 4 – Nitrogen Oxides from Natural Gas-Fired Furnaces. Available at: https://www.baaqmd.gov/~/media/dotgov/files/rules/reg-9-rule-4-nitrogen-oxides-from-fan-type-residential-central-furnaces/2021-amendments/documents/20230315_rg0904-pdf.pdf?rev=fd4b39bc0c834bcbba8b76646526afc6&sc_lang=en

    BAAQMD. 2023c. Final Staff Report: Proposed Amendments to Building Appliance Rules – Regulation 9, Rule 4: Nitrogen Oxides from Fan Type Residential Central Furnaces and Rule 6: Nitrogen Oxides Emissions from Natural Gas-Fired Boilers and Water Heaters. 54 pp. Jennifer Elwell, Eric Lara.

    CARB. 2010. Title 17 California Code of Regulations (CCR) Public Health, Division 3 Air Resources, Chapter 1 Air Resources Board, Subchapter 10 Climate Change, Article 4 Regulation to Achieve Greenhouse Gas Emissions Reductions, Subarticle 3.1 Regulation for Reducing Sulfur Hexafluoride Emissions from Gas Insulated Switchgear, Section 95350 to 95359. Available here: https://ww2.arb.ca.gov/our-work/programs/elec-tandd/regulation

    CARB. 2019. California Air Resources Board - Regulation for the Mandatory Reporting of Greenhouse Gas Emissions. https://ww2.arb.ca.gov/sites/default/files/classic/cc/reporting/ghg-rep/regulation/mrr-2018-unofficial-2019-4-3.pdf

    CARB. 2021. Title 13 California Code of Regulations (CCR), Section 95350 to 95359, Subchapter 10 Climate Change. Article 4 Regulation to Achieve Greenhouse Gas Emissions Reductions. Subarticle 3.1. Regulation for Reducing Sulfur Hexafluoride Emissions from Gas Insulated Switchgear. Available here: https://ww2.arb.ca.gov/our-work/programs/elec-tandd/regulation

    CEC. 2018. Natural Gas Methane Emissions from California Homes. Marc L. Fischer, Wanyu R. Chan, Seonguen Jeong, Zhimin Zhu. Publication Number: CEC-500-2018-021.

    CEC. 2020a. 2019 California Residential Appliance Saturation Study. DNV GL Energy Insights USA, Inc. Publication Number: CEC-200-2021-005-PO

    CEC. 2020b. Characterization of Fugitive Methane Emissions from Commercial Buildings in California, Johnston, E., Bluestein, J., Liu, J., Kanaan, J., Cohen, J., Cooper, W.,2020, Characterization of Fugitive Methane Emissions from Commercial Buildings in California. California Energy Commission. Publication Number: CEC-500-2020-048.
    https://www.energy.ca.gov/sites/default/files/2021-05/CEC-500-2020-048.pdf

    CEC. 2020c. Evaluation and Identification of Constituents in Pipeline Natural Gas, Biogas, and Biomethane in California: Wastewater Treatment, Green Waste, and Landfills, California Energy Commission. Publication Number: CEC-500-2020-048.
    https://www.energy.ca.gov/sites/default/files/2021-05/CEC-500-2020-031.pdf

    CEC. 2023a. California Energy Commission (CEC) Natural Gas Usage in MMTherms by County and by Residential and Non-Residential sectors, 1990 – 2022. Downloaded September 23, 2023. Available at: http://www.ecdms.energy.ca.gov/gasbycounty.aspx

    CEC. 2023b. 2023 Integrated Energy Policy Report (IERP). Bailey, Stephanie, Jennifer Campagna, Mathew Cooper, Quentin Gee, Heidi Javanbakht, and Ben Wender. Publication Number: CEC-100-2023-001-CMF. https://www.energy.ca.gov/data-reports/reports/integrated-energy-policy-report/2023-integrated-energy-policy-report.

    CEC. 2024. Suggested Forecast Scenarios for Residential and Commercial Natural Gas Usage by Service Area. Personal communication with N. Janusch, Program and Project Supervisor, Efficiency Analysis Unit, Advanced Electrification Analysis Branch, Energy Assessments Division on June 27, 2024.

    Greenblatt. 2013. Estimating Policy-Driven Greenhouse Gas Emissions Trajectories in California: The California Greenhouse Gas Inventory Spreadsheet (GHGIS) Model. LBNL6451E. November 2013. http://eetd.lbl.gov/publications/estimating-policy-drivengreenhouse-g

    IPCC. 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II, and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyers (eds.)]. IPCC, Geneva, Switzerland, 151 pp. Available here: https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf

    IPCC. 1995. IPCC Second Assessment Climate Change 1995, A Report of the Intergovernmental Panel on Climate Change. 63 pp. Available here: https://www.ipcc.ch/site/assets/uploads/2018/02/2nd-assessment-en_SYR.pdf

    USEPA. 2016. Title 40 Code of Federal Regulations (CFR), Subpart C, Part 98, Subpart C – General Stationary Fuel Combustion Sources. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-98/subpart-C?toc=1

    USEPA. 1998. AP-42, Fifth Edition, Volume I, Compilation of Air Emissions Factors from Stationary Source, Chapter 1 External Combustion Sources, Subchapter 4 Natural Gas Combustion. https://www.epa.gov/sites/default/files/2020-09/documents/1.4_natural_gas_combustion.pdf